1. Field of the Invention
The present invention relates to an image forming apparatus having a supporting member on which a plurality of cartridges are adapted to be mounted in a detachable manner.
2. Description of the Related Art
In an image forming apparatus using an electrophotographic image forming process, there has been adopted a system in which at least one of an electrophotographic photosensitive member, a process unit acting on the electrophotographic photosensitive member, and a developer storage portion with a developer stored therein is formed into a cartridge and is detachably attached to an image forming apparatus main body. According to such a cartridge system, a user is able to perform the maintenance of the apparatus without resort to a serviceman. As a result, convenience and efficiency in operation of the apparatus can be improved to a remarkable extent. Therefore, such a cartridge system has been used in a lot of electrophotographic image forming apparatuses.
For such a detachable construction of a cartridge, there is known a system in which a cartridge being carried on a tray is drawn out for detachment and attachment thereof (see Japanese patent application laid-open No. 2006-184901 and U.S. Pat. No. 2005147432).
However, in an image forming apparatus that has a drawer or tray to which a plurality of cartridges can be attached, in case where only a specific cartridge is made larger in size because of a large amount of consumption of a specific developer contained in the specific cartridge, etc., there will be a possibility that the image forming apparatus might have to be increased in size, or a waste of space might occur.